Cores de Identificação
The GGD D6 steel is a steel for cold working with high fraction of carbides and high hardness after heat treatment. These characteristics make this steel a high wear resistance superior to the GGD D2. However, this steel is more brittle than the steel GGD D2.
Supply conditions – Supplied in the annealed condition with a maximum hardness of 250 HB.
Their high hardness makes it especially suitable for severe wear applications such as forming operations and cold cut on sliding surfaces and molds for ceramics. It is used in cutting tools like knives, dies, punches, scissors. In escariadores, mandrels, drawing dies, gauges, etc.
Stress relief: In tools of complex shapes, with heterogeneous material removal in roughing, sudden change of sections, etc., before hardening in tempering should be performed the treatment of stress relief to minimize dimensional variations. Treatment should be done at 550 ° C temperature for at least 1 hour for every 25 mm. Then cool in
oven to at least 200 ° C and then in still air.
Tempering: When heating for austenitization to be performed pre-heating to ensure temperature uniformity and minimize distortion. Preheat at temperature of 550 ° C. Austenize in temperature between 950 – 970ºC. Heat for 1 hour for each 25 mm thick and add 1 additional hour for each 25 mm. Preferably cooling oil
pre-heated to around 70 ° C under stirring. It can also be cooled in still air.
Tempering: It must be done immediately after hardening when the temperature reaches about 70 ° C. The tempering temperature should be selected according to the specified hardness. As this steel does not have secondary hardening, tempering must be around 200 ° C, but never below 180 ° C. For this use as a guide the tempering curve below. Keeping the tempering temperature for at least 1 hour for each 25 mm thick and used at least double tempering. Using a minimum time of 2 hours and held at the minimum of two tempering.
Nitriding: The steel can be nitrided to increase the wear resistance of the surface hardening. However, the nitriding process should be controlled so as not to significantly decrease the hardness of the tool body. The nitriding of this steel can not lead to the formation of the White layer, because weakens the nitrided surface. The maximum hardness after nitriding is in the range of 900 – 1000HV, depending on the initial hardness after processing.
EDM and grinding: The steel GGD D6 is susceptible to the appearance of cracks after these processes. When performed outside the box, the EDM and grinding can cause retempers surface, deteriorating the heat treatment in the region and lead to the formation of cracks. In extreme cases it can cause loss tool for cracking and fracture. If necessary perform a new tempering after finishing tool.Z